Field of the Invention
An embodiment of the present invention relates to a position detecting device, and a projector having a position detecting function.
Description of the Related Art
Recently, a projector having an interactive function with which it is possible to input a position on a projected screen has appeared. This projector can not only project an image but also input positional information in real time with touch operation. Accordingly, it is possible to input operation information (positional information) only with a touch on a projection screen without operation of a mouse and to easily realize an electronic blackboard function. That is, it is possible to provide a projection screen of a projector as a pseudo touch panel on which operation or writing can be performed with a direct touch.
Similarly, there is a product called a laser keyboard with which it is possible to perform a key input by projection of a keyboard image with a laser beam on a plane surface and by a touch on the keyboard image. Since the laser keyboard can realize a keyboard function in a compact manner with a projection unit and a camera, the laser keyboard is suitable for a keyboard for a mobile device such as a smartphone. After pairing a laser keyboard and a smartphone, for example, by Bluetooth (registered trademark), a user places the laser keyboard on a desk, touches a keyboard projected with a laser beam, and performs a key input.
In Japanese Patent Application Laid-Open No. 2015-064550, an invention related to what is similar to the above-described projector is disclosed.
As illustrated in FIG. 6, in a case of using a glossy desk 1 as a pseudo touch panel, infrared light reflected at a light blocking point PO on a finger 3 includes a light beam, which is reflected again on a glossy surface of the desk 1 and passes through a wrong optical path Lg entering an IR camera 22, other than a light beam that passes through a correct optical path Lr directly entering the IR camera 22.
When reflection intensity of the desk 1 is low, there is no problem. However, when the desk 1 is glossy and reflection intensity thereof is high, in a case where intensity of an unnecessary light beam passing through the wrong optical path Lg exceeds a threshold, it is determined that there is a pseudo light blocking point P2 and a wrong touch position R1 is erroneously recognized.
Thus, an embodiment of the present invention is to prevent erroneous recognition of a touch position in a position detecting device or a projector to detect a touch position with a camera.